2.1 Hematological Malignancies
Hematological malignancies are cancers of the body's blood-forming and immune systems. Hematological malignancies include leukemia, lymphoma (both Hodgkin's disease and non-Hodgkin's lymphoma), and myeloma. The abnormal cell growth interferes with the body's production of healthy blood cells, thus making the body unable to protect itself against infections.
New cases of hematological malignancies account for 9 percent of cancer cases diagnosed in the United States, and about 59,200 persons are killed by the diseases each year. Many of these disease occur in children.
2.1.1 Leukemia
Leukemia is a cancer of the bone marrow and blood. It is characterized by the uncontrolled growth of blood cells. About 30,000 new cases of leukemia in the United States are reported each year. Most cases occur in older adults, though leukemia is the most common type of childhood cancer.
Leukemia is either acute or chronic. In acute leukemia, the abnormal blood cells are blasts that remain very immature and cannot carry out their normal functions. The number of blasts increases rapidly, and the disease gets worse quickly. In chronic leukemia, some blast cells are present, but in general, these cells are more mature and can carry out some of their normal functions. Also, the number of blasts increases less rapidly than in acute leukemia. As a result, chronic leukemia gets worse gradually.
Leukemia can arise in either of the two main types of white blood cells—lymphoid cells (lymphocytic leukemia) or myeloid cells (myeloid or myelogenous leukemia). Common types of leukemia include acute lymphocytic leukemia (ALL); acute myeloid leukemia (AML) (sometimes called acute nonlymphocytic leukemia (ANLL)) such as myeloblastic, promyelocytic, myelomonocytic, monocytic, erythroleukemia leukemias and myelodysplastic syndrome; chronic lymphocytic leukemia (CLL); chronic myeloid (granulocytic) leukemia (CML); chronic myelomonocytic leukemia (CMML); hairy cell leukemia; and polycythemia vera.
2.1.2 Lymphoma
There are two main types of lymphoma—Hodgkin's disease and non-Hodgkin's lymphoma. Hodgkin's disease, also known as Hodgkin's lymphoma, is a special form of lymphoma in which there is a particular cell known as the Reed Sternberg (R-S) cell. This cell is not usually found in other lymphomas.
The cause for Hodgkin's disease is unknown. Hodgkin's disease, like other cancers, is not infectious and cannot be passed onto other people. It is not inherited. The first symptom of Hodgkin's disease is usually a painless swelling in the neck, armpits or groin. Other symptoms may include night sweats or unexplained fever, weight loss and tiredness, cough or breathlessness, and persistent itch all over the body.
There are about 20 different types of non-Hodgkin's lymphoma. Non-Hodgkin's lymphomas are categorized according to their appearance under the microscope and the cell type (B-cell or T-cell). Risk factors include old age, female, weakened immune system, human T-lymphotropic virus type 1 (HTLV-1) and Epstein-Barr virus infection, and exposure to chemicals such as pesticides, solvents, and fertilizers.
2.1.3 Myeloma
Myeloma is a malignant tumor composed of plasma cells of the type normally found in the bone marrow. Myeloma cells tend to collect in the bone marrow and in the hard, outer part of bones. Sometimes they collect in only one bone and form a single mass, or tumor, called a plasmacytoma. In most cases, however, the myeloma cells collect in many bones, often forming many tumors and causing other problems. When this happens, the disease is called multiple myeloma such as but not limited to giant cell myeloma, indolent myeloma, localized myeloma, multiple myeloma, plasma cell myeloma, sclerosing myeloma, solitary myeloma, smoldering multiple myeloma, nonsecretary myeloma, osteosclerotic myeloma, plasma cell leukemia, solitary plasmacytoma, and extramedullary plasmacytoma.
Myelodysplastic syndromes are disorders in which the bone marrow produces ineffective and abnormal looking cells on one or more types (white blood cells, red blood cells or platelets). The majority of patients are men over sixty. Secondary myelodysplastic syndromes are seen following the use of chemotherapy and irradiation.
Signs and symptoms depend on the types of cells that are affected. Abnormal white cells make people more susceptible to infections; abnormal platelets make people more susceptible to bruising and spontaneous hemorrhages; and abnormal red blood cells causes anemia and fatigue.
While chemotherapy and radiation are useful in the treatment of hematological malignancies, there is a continued need to find better treatment modalities and approaches to manage the disease that are more effective and less toxic, especially when clinical oncologists are giving increased attention to the quality of life of cancer patients. The present invention provides an alternative approach to hematological malignancies therapy and management of the disease by using an oral composition comprising arsenic trioxide.
2.2 Arsenic
Arsenic has been used medicinally for over 2,000 years. In the 18th century, a solution of arsenic trioxide (empirical formula As2O3) in 1% w/v potassium bicarbonate (Fowler's solution) was developed to treat a variety of infectious and malignant diseases. Its efficacy in suppressing white cells was first described in 1878 (Kwong Y. L. et al. Delicious poison: arsenic trioxide for the treatment of leukemia, Blood 1997;89:3487-8). Arsenic trioxide was therefore used to treat chronic myelogenous leukemia, until more potent cytotoxic drugs superseded it in the 1940s. However, there was a resurgence of interest in such therapy, when arsenic trioxide was found to induce apoptosis and differentiation in acute promyelocytic leukemia (APL) cells (Chen G. Q. et al. Use of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL): I. As2O3 exerts dose-dependent dual effect on APL cells in vitro and in vivo, Blood 1997;89:3345-53; Soignet S. L. et al. United States multicenter study of arsenic trioxide in relapsed acute promyelocytic leukemia. J Clin Oncol. 2001;19:3852-60). The clinical implications of these in vitro observations have since been verified, as arsenic trioxide induces remissions in over 90% of such patients (Shen Z. X. et al. Use of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL): II. Clinical efficacy and pharmacokinetics in relapsed patients, Blood 1997;89:3354-60; Soignet S. L. et al. Complete remission after treatment of acute promyelocytic leukemia with arsenic trioxide, N Engl J Med 1998;339:1341-8; Niu C. et al., Studies on treatment of acute promyelocytic leukemia with arsenic trioxide: remission induction, follow-up and molecular monitoring in 11 newly diagnosed and 47 relapsed acute promyelocytic leukemia patients, Blood 1999;94:3315-24).
A typical course of arsenic trioxide involves daily intravenous (IV) administration for 4 to 8 weeks and the attendant inconvenience, risks and expense of maintaining suitable vascular access and prolonged hospitalization. Currently, there is no oral arsenic trioxide for clinical use. Fowler's solution is no longer detailed in modem pharmacopoeias or listed in formularies (1941, Arsenum. Martindale, The Extra Pharmacopoeia 22:209-15; British Pharmacopoeia. London: Her Majesty's Stationery Office, 1988; Appendix 1A, p A12). Formulation of arsenic trioxide for oral administration could therefore offer distinct advantages. The inventors have recently developed an oral preparation of arsenic trioxide useful for achieving total blood cell and plasma levels of elemental arsenic comparable with those of intravenous arsenic trioxide (Kumana C. R. et al. Systemic availability of oral arsenic-trioxide used for treatment of patients with haematological malignancies. Eur J Clin Pharmacol. 2002;58:521-526, which is incorporated by reference herein in its entirety).